The invention relates to a gamma camera comprising a scintillator crystal with a pinhole collimator, at least four optoelectronic transducers with amplifiers and an evaluation unit.
Such a camera is known for example from Hermann, H. J. Nuklearmedizin, publisher: Urban & Schwarzenberg, Munich, 3rd edition 1992.
Gamma cameras known in the art consist generally of a large area NaI(T1)-crystal provided at its front side with a collimator and, at its backside, with an arrangement of up to 90 photomultipliers. The sensitivity and the spatial resolution capability are determined mainly by the area of the NaI(T1)-crystal and the structure of the collimator. The best spatial resolution capability is obtained, at this time, with so-called pin hole collimators with small opening diameters; however, the sensitivity of such a camera is relatively low. To increase the sensitivity, it is possible to use several cameras simultaneously. However, because of the relatively large dimensions of the cameras, the space limits are rapidly reached.
U.S. Pat. No. 3,855,473 discloses scintillator crystals with upwardly widening collimators, optoelectronic transducers including amplifiers and an evaluation unit wherein the scintillators are hollow bodies which are open at one side. However, they do not provide for a high spatial resolution.
In addition, U.S. Pat. No. 4,348,591 discloses a gamma camera of the type referred to above which, however, has a very small field of vision because the pinhole collimator has the shape of a recessed structure.